Uveitis is an especially challenging group of diseases to diagnose, treat, and elucidate because the causes are multiple and animal models may not always reflect the chronicity and complexity of human disease. We now propose two sets of experiments to build on our prior observations and to clarify the pathogenesis of anterior uveitis. First, we will test the hypothesis that the endothelium of the iris microvasculature can be distinguished from the microvasculature in other tissues such as the retina. Many observations from other organ systems support the contention that the microvascular endothelium differs relative to specific organ beds. We have succeeded in establishing highly purified cultures of iris and retina microvascular endothelial cells from the same human donor eye. We will characterize the biology of these iris microvascular cells by utilizing cDNA microarray to identify differences that distinguish the iris endothelium from other vasculature. A corollary to these studies is the use of Woodruff-Stamper binding assays to determine if lymphocytes from patients with anterior uveitis bind preferentially to anterior segment vessels and conversely if lymphocytes from patients with posterior uveitis preferentially bind to posterior segment vessels. The uniqueness of the vasculature could potentially identify a highly specific target for anti-inflammatory therapy and could certainly clarify the pathogenesis of anterior uveitis. Second we will exploit the technology of time-lapse video microscopy of leukocyte migration in the iris stroma to determine the signals that mediate extravascular neutrophil migration within a tissue plane. We hypothesize specifically that neutralization of a) beta1-integrin, b) L selectin, c) CD47 or d) discoidin domain receptor 1; or the addition of tenascin will markedly reduce leukocyte migration within tissue, while blocking CD44 should enhance neutrophil migration. We hypothesize further that neutralizing chemokines, KC or MIP2, will have no effect. Complementing these studies, we will study the role of matrilysin in migration of cells out of the tissue plane into the aqueous humor. We believe that these aims are novel, innovative, especially suited to the skills and achievements demonstrated by our laboratory, and highly relevant to clarifying the pathogenesis of anterior uveitis.